libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997, 2002, 2011 Free Software Foundation,
   2    Inc.
   3    This file based on setenv.c in the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  18    Boston, MA 02110-1301, USA.  */
  19
  20
  21 /*
  22
  23 @deftypefn Supplemental int setenv (const char *@var{name}, @
  24   const char *@var{value}, int @var{overwrite})
  25 @deftypefnx Supplemental void unsetenv (const char *@var{name})
  26
  27 @code{setenv} adds @var{name} to the environment with value
  28 @var{value}.  If the name was already present in the environment,
  29 the new value will be stored only if @var{overwrite} is nonzero.
  30 The companion @code{unsetenv} function removes @var{name} from the
  31 environment.  This implementation is not safe for multithreaded code.
  32
  33 @end deftypefn
  34
  35 */
  36
  37 #if HAVE_CONFIG_H
  38 # include <config.h>
  39 #endif
  40
  41 #define setenv libiberty_setenv
  42 #define unsetenv libiberty_unsetenv
  43
  44 #include "ansidecl.h"
  45 #include <sys/types.h> /* For `size_t' */
  46 #include <stdio.h>     /* For `NULL' */
  47
  48 #include <errno.h>
  49 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  50 extern int errno;
  51 #endif
  52 #define __set_errno(ev) ((errno) = (ev))
  53
  54 #if HAVE_STDLIB_H
  55 # include <stdlib.h>
  56 #endif
  57 #if HAVE_STRING_H
  58 # include <string.h>
  59 #endif
  60 #if HAVE_UNISTD_H
  61 # include <unistd.h>
  62 #endif
  63
  64 #define __environ       environ
  65 #ifndef HAVE_ENVIRON_DECL
  66 #ifndef environ
  67 extern char **environ;
  68 #endif
  69 #endif
  70
  71 #undef setenv
  72 #undef unsetenv
  73
  74 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  75  * implementation MT-Unsafe. */
  76 #define LOCK
  77 #define UNLOCK
  78
  79 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  80
  81 /* If this variable is not a null pointer we allocated the current
  82    environment.  */
  83 static char **last_environ;
  84
  85
  86 int
  87 setenv (const char *name, const char *value, int replace)
  88 {
  89   register char **ep = 0;
  90   register size_t size;
  91   const size_t namelen = strlen (name);
  92   const size_t vallen = strlen (value) + 1;
  93
  94   LOCK;
  95
  96   size = 0;
  97   if (__environ != NULL)
  98     {
  99       for (ep = __environ; *ep != NULL; ++ep)
 100         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
 101           break;
 102         else
 103           ++size;
 104     }
 105
 106   if (__environ == NULL || *ep == NULL)
 107     {
 108       char **new_environ;
 109       if (__environ == last_environ && __environ != NULL)
 110         /* We allocated this space; we can extend it.  */
 111         new_environ = (char **) realloc (last_environ,
 112                                          (size + 2) * sizeof (char *));
 113       else
 114         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 115
 116       if (new_environ == NULL)
 117         {
 118           UNLOCK;
 119           return -1;
 120         }
 121
 122       new_environ[size] = (char *) malloc (namelen + 1 + vallen);
 123       if (new_environ[size] == NULL)
 124         {
 125           free ((char *) new_environ);
 126           __set_errno (ENOMEM);
 127           UNLOCK;
 128           return -1;
 129         }
 130
 131       if (__environ != last_environ)
 132         memcpy ((char *) new_environ, (char *) __environ,
 133                 size * sizeof (char *));
 134
 135       memcpy (new_environ[size], name, namelen);
 136       new_environ[size][namelen] = '=';
 137       memcpy (&new_environ[size][namelen + 1], value, vallen);
 138
 139       new_environ[size + 1] = NULL;
 140
 141       last_environ = __environ = new_environ;
 142     }
 143   else if (replace)
 144     {
 145       size_t len = strlen (*ep);
 146       if (len + 1 < namelen + 1 + vallen)
 147         {
 148           /* The existing string is too short; malloc a new one.  */
 149           char *new_string = (char *) malloc (namelen + 1 + vallen);
 150           if (new_string == NULL)
 151             {
 152               UNLOCK;
 153               return -1;
 154             }
 155           *ep = new_string;
 156         }
 157       memcpy (*ep, name, namelen);
 158       (*ep)[namelen] = '=';
 159       memcpy (&(*ep)[namelen + 1], value, vallen);
 160     }
 161
 162   UNLOCK;
 163
 164   return 0;
 165 }
 166
 167 void
 168 unsetenv (const char *name)
 169 {
 170   const size_t len = strlen (name);
 171   char **ep;
 172
 173   LOCK;
 174
 175   for (ep = __environ; *ep; ++ep)
 176     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 177       {
 178         /* Found it.  Remove this pointer by moving later ones back.  */
 179         char **dp = ep;
 180         do
 181           dp[0] = dp[1];
 182         while (*dp++);
 183         /* Continue the loop in case NAME appears again.  */
 184       }
 185
 186   UNLOCK;
 187 }